A239838 Number of ordered pairs of permutation functions on n elements where f(f(f(x))) = g(g(g(x))).

1, 1, 2, 12, 96, 600, 9360, 146160, 1935360, 41368320, 1092268800, 23111827200, 700300339200, 26141033318400, 810322216704000, 31624796915712000, 1537594906079232000, 63980698878480384000, 3128302230597992448000, 187447679378885173248000

Offset

0,3

Links

Hiroaki Yamanouchi, Table of n, a(n) for n = 0..60

Hiroaki Yamanouchi, Python code

Crossrefs

Cf. A000012, A000085, A000142, A088311, A053529, A001044.

a(n) = n! * A232207(n) for n>0. - Alois P. Heinz, Jul 23 2014

Sequence in context: A366334 A247075 A239837 * A306258 A052691 A371040

Adjacent sequences: A239835 A239836 A239837 * A239839 A239840 A239841

Keyword

nonn

Author

Chad Brewbaker, Mar 27 2014

Extensions

a(8)-a(12) from Giovanni Resta, Mar 27 2014

a(13) from Alois P. Heinz, Jul 23 2014

a(14)-a(19) from Hiroaki Yamanouchi, Mar 12 2015

Status

approved